KR20130061052A - Adhesive composition for polarizing plate and polarizing plate using the same - Google Patents

Abstract

PURPOSE: An adhesive composition for a polarizing plate is provided to restrain the generation and propagation of cracks. CONSTITUTION: An adhesive composition for a polarizing plate comprises 100.0 parts by weight of a polyvinylalcohol-based resin, 20-300 parts by weight of a fumed metal compound, and 5-40 parts by weight of a hardener. The fumed metal compound has a volume density of 0.03-0.10 g/cm^3, a specific surface area of 100-400 m^2/g, and a first particle diameter of 5-50 nm. The viscosity of the polarizing plate adhesive composition is 1-50 mPa·s. A polarizing plate comprises the polarizing plate and a protection film, which are attached to each other. [Reference numerals] (AA) Polarizer; (BB) Adhesive solution; (CC) Polarizing plate before drying

Description

Adhesive composition for polarizing plates and polarizing plate using the same {ADHESIVE COMPOSITION FOR POLARIZING PLATE AND POLARIZING PLATE USING THE SAME}

The present invention relates to an adhesive composition for polarizing plates and a polarizing plate using the same.

In recent years, flat-panel displays such as liquid crystal displays, plasma displays, and organic electroluminescent displays have been widely used in terms of space saving, power saving, and high definition. In particular, with respect to liquid crystal displays, with the spread of digitized electronic devices, the status as general display devices has been established. The liquid crystal display is currently widely used in televisions, computers, mobile phones, portable game machines, electronic calculators, watches, and the like.

A liquid crystal display (LCD) usually includes a light source, a driving circuit, a power supply circuit, a connection connector, and a liquid crystal panel. The liquid crystal display adjusts the transmission of light emitted from the light source by modulating the alignment of the liquid crystal panel, and the transmitted light is emitted to display a screen. In addition, the driving circuit and the power supply circuit modulate the orientation of the liquid crystal panel by controlling the voltage. Since the liquid crystal display has such an image display mechanism, the light incident on the liquid crystal panel needs to be linearly polarized light, and the light emitted from the liquid crystal panel needs to be polarized light in a specific direction. Therefore, generally, a liquid crystal panel has a structure comprised between polarizing plates.

The polarizing plate includes a polarizer, an adhesive layer and a protective film. The polarizer passes only light in a specific direction and blocks other light. Usually, the polarizer is produced by crosslinking a dye obtained by dyeing an iodine compound on a polyvinyl alcohol (PVA) film in one direction. For this reason, it is easy to tear in an extending | stretching direction, and a polarizer is applied by strengthening intensity | strength one side or both surfaces with a protective film. The said polarizer and a protective film are adhere | attached by an adhesive layer. Thus, when both surfaces of the polarizer are reinforced with a protective film, the polarizing plate has a structure in which a protective film-adhesive layer-polarizer-adhesive layer-protective film is laminated in this order. The polarizing plate which has the said structure is manufactured by bonding a polarizer with a protective film through the solution containing an adhesive agent, and then drying and forming an adhesive layer.

Since a polarizer is easy to tear in a extending | stretching direction, a polarizer crack may generate | occur | produce also when using a protective film. This is due to the polarizer being bonded to the protective film in the stretched state. For example, the polarizer in the polarizing plate manufactured by the unevenness | corrugation which arises in the interface of a polarizer and a protective film in a manufacturing process, etc. may be deform | transformed, and a polarizer crack may arise by the deformation of the said polarizer.

As a method of suppressing the polarizer crack, a method of studying the constitution of the adhesive has been proposed. For example, JP 2008-15483 discloses an adhesive for polarizing plates containing a polyvinyl alcohol-based resin, a crosslinking agent, and a metal colloid having a specific particle size. According to said JP 2008-15483, when using the said adhesive agent for polarizing plates, it can describe that generation | occurrence | production of the local uneven | corrugated defect which arises at the interface when a polarizer and a transparent protective film are stuck together is described.

However, when the adhesive for polarizing plates of Patent Literature 1 is used, fine irregularities called orange peels are formed on the surface of the polarizing plate, resulting in poor appearance of the polarizing plate and distortion of the display image. It turned out that it could.

An object of this invention is to provide the adhesive composition for polarizing plates which can suppress a polarizer crack and generation | occurrence | production of an orange peel.

As a result of intensive studies, the present inventors have found that the above problems can be solved by using a polyvinyl alcohol-based resin, a fumed metal compound, and an adhesive composition for a polarizing plate each containing a predetermined amount of a curing agent. The present invention has been completed.

That is, this invention relates to the adhesive composition for polarizing plates containing 100 mass parts of polyvinyl alcohol-type resins, 20-300 mass parts of fumed metal compounds, and 5-40 mass parts of hardening | curing agents.

According to the adhesive composition for polarizing plates which concerns on this invention, generation | occurrence | production of a polarizer crack and an orange peel can be suppressed.

1 is a schematic view for explaining a manufacturing step of a polarizing plate in an embodiment;
FIG. 2 is a schematic view for explaining a method of a thermal shock test in Examples, FIG. 2 (a) is a schematic cross-sectional view showing the structure of a test piece, and FIG. ;
3 is a schematic cross-sectional view for explaining the method of the forced peeling test in the embodiment.

According to one Embodiment of this invention, the adhesive composition for polarizing plates containing a polyvinyl alcohol-type resin, a fumed metal compound, and a hardening | curing agent (henceforth simply an "adhesive composition") is provided.

[Polyvinyl Alcohol Resin]

Polyvinyl alcohol-type resin provides adhesiveness to an adhesive composition.

There is no restriction | limiting in particular as polyvinyl alcohol-type resin, A well-known thing can be used. Specifically, Polyvinyl alcohol obtained by saponifying polyvinyl acetate; Polyvinyl alcohol obtained by saponifying a copolymer of polyvinyl acetate and other monomers; Modified polyvinyl alcohol and the like.

As another monomer copolymerizable with polyvinyl acetate, Unsaturated carboxylic acid, its ester, sulfonic acid; alpha-olefin; Unsaturated nitriles; Unsaturated amides; Aromatic vinyls; Aliphatic vinyls; And unsaturated bond-containing heterocycles. Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic anhydride, itaconic acid, and the like. Butyl acrylate, hydroxyethyl acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, polyethylene glycol Lycol methacrylate, etc. As sulfonic acids of unsaturated carboxylic acid, sodium metaaryl sulfonate, sodium monoalkyl maleic acid sulfonate, sodium alkyl sulfonic acid disulfonic acid, etc. are mentioned. Ethylene, propylene, butadiene, etc. As the unsaturated nitriles, acryl Yttryl and methacrylonitrile include acrylamide, dimethylacrylamide, methacrylamide and N-methylol acrylamide as the unsaturated amides. Methyl styrene is mentioned As an aliphatic vinyl, vinyl acetate is mentioned As an unsaturated bond containing heterocyclic ring, N-vinylpyrrolidone and acryloyl morpholine are mentioned.

Modified polyvinyl alcohol is one or two or more optional treatments of polyvinyl alcohol obtained by saponifying the polyvinyl acetate or polyvinyl alcohol obtained by saponifying a copolymer of polyvinyl acetate and other monomers. . For example, the modified polyvinyl alcohol may be amine modified, ethylene modified, carboxylic acid modified, urethane modified, diacetone modified, thiol modified, phosphate ester modified, acetoacetyl modified. Moreover, you may use modified polyvinyl alcohol in which cation modification, anion modification, or nonionic modification is carried out.

It is preferable to use acetoacetyl modified polyvinyl alcohol resin among the above-mentioned polyvinyl alcohol-type resin. Since acetoacetyl group has high reactivity, when it is used for the adhesive for polarizing plates, it can show high durability by being highly crosslinked. Acetoacetyl-modified polyvinyl alcohol can be obtained by making polyvinyl alcohol-type resin and diketene react by a well-known method. Specifically, a polyvinyl alcohol-based resin is dispersed in a solvent such as acetic acid, and a method of adding diketene thereto, and a polyvinyl alcohol-based resin is previously dissolved in a solvent such as dimethylformamide or dioxane. The method of adding a diketene, the method of directly contacting a diketene gas or a liquid diketene with polyvinyl alcohol, etc. are mentioned.

Although the polyvinyl alcohol-type resin mentioned above can also be synthesize | combined and used, you may use a commercial item. As a commercial item, it is a Gocepama (trademark) ZZ-100, Z-200, Z-205, Z-210, Z-300, Z-320, Z-410 (made by Nihon Kosei Kagaku Kogyo Co., Ltd.); Kurare Povar PVA-117, PVA-217 (manufactured by Kuraray Co., Ltd.); Tenka Povar (registered trademark) K-05, K17-E, K-17C, H-12, H-17, PC-1000 (made by Denki Kagaku Co., Ltd.), etc. are mentioned. Among these, it is preferable to use Gosefima (registered trademark) ZZ-200 and Z-410 (made by Nihon Kosei Chemical Co., Ltd.).

The above-mentioned polyvinyl alcohol-type resin may be used independently, or may mix and use 2 or more types.

It is preferable that it is 500-3000, and, as for the polymerization degree of polyvinyl alcohol-type resin, it is more preferable that it is 1000-2000. If the degree of polymerization is 500 or more, it is preferable in view of excellent durability and heat resistance. On the other hand, when polymerization degree is 3000 or less, since a viscosity does not become high too much and adhesive composition becomes a uniform thickness between a polarizer and a protective film, it is preferable.

Moreover, it is preferable that it is 90-100 mol%, and, as for the saponification degree of polyvinyl alcohol-type resin, it is more preferable that it is 96-99 mol%. If saponification degree is 90 mol% or more, it is preferable at the point which is excellent in durability and heat resistance. As can be clearly seen from the value of the above preferred saponification degree, polyvinyl alcohol exhibits adhesiveness by a number of hydroxyl groups which it has.

[Fumed metal compound]

The fumed metal compound can suppress generation of polarizer cracks and orange peels. Here, "fumed metal compound" means an aggregate of a metal compound having a structure in which primary particles of the metal compound are aggregated in an amorphous form.

Examples of the metal compound included in the fumed metal compound include silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), zinc oxide (ZnO ₂ ), and zirconium oxide ( ZrO ₂ ), cerium oxide (CeO ₂ ), and the like. Among these, the fumed metal compound preferably contains silicon oxide, aluminum oxide, or titanium oxide.

Examples of the fumed metal compound having a structure in which the metal compound is aggregated in an amorphous form include fumed silica, fumed alumina, fumed titania, fumed zirconia, and fumed ceria. The fumed metal compound may be a mixed fumed metal compound containing two or more kinds of the above metal compounds. Among these fumed metal compounds, it is preferable to use fumed silica, fumed alumina, or mixed fumed metal compounds of silicon oxide and aluminum oxide.

The fumed metal compound may be a surface-treated fumed metal compound. For example, in the case of fumed silica, for silanol groups present on the surface, dimethylsilylation with dimethyldichlorosilane, trimethylsilylation with hexamethyldisilazane, octylsilylation with octylsilane, Surface treatment, such as dimethyl polysiloxane conversion by silicone oil, can be performed. By performing the surface treatment, at least one of the hydrophilic groups of the fumed metal compound can be modified with a hydrophobic group.

The said fumed metal compound may be used directly, and a commercial item may be used. For example, fumed silica can be prepared by high temperature hydrolysis of silicon tetrachloride (SiCl ₄ ) in an oxyhydrogen flame. In addition, as a commercial item, Aerosol (registered trademark) 50, 90G, 130, 200, 200CF, 200V, 200FAD, 300, 300CF, 380, OX50, TT600, MOX80, MOX170, COK84, Airoxide (registered trademark) AluCu, Alu65 Hydrophilic fumed metal compounds such as, Alu30, TiO ₂ P25, TiO ₂ P90 (manufactured by Nippon Aerosil Co., Ltd.), Aerosol® R972, R972CF, R972V, R9200, R974, R9765, R104, R106, RX50, NAX50, NX90G, RX200, RX300, R812, R812S, R8200, RA200H, RA200HS, RY50, NY50, RY2005, RY200, RY300, R200, R805, R711, R7200, Airoxide (registered trademark) Alu805, TiO ₂ T805, TiO ₂ PNKT90 Hydrophobic fumed metal compounds, such as these, can be used.

The above-described fumed metal compounds may be used alone or in combination of two or more kinds thereof.

It is preferable that a fumed metal compound has at least 1 hydrophilic group. The hydrophilic group (if fumed silica, silanol group) of the fumed metal compound is present on the particle surface, and the hydrophilic group can contribute to suppression of polarizer cracking and orange peel. A polarizer crack and an orange peel may arise mainly because it sticks with a protective film in the state in which the polarizer was extended. Specifically, a polarizer crack can arise because a polarizer deforms with a change of the stress of the adhesive composition in the manufacturing process of a polarizing plate. In addition, since an orange peel uses an adhesive composition in a solution state at the time of the manufacturing process of a polarizing plate, it may arise because the said solution component transfers inside a polarizer, a polarizer deform | transforms, and even if it is dried, the said deformation does not return to original. The hydrophilic group of the fumed metal compound may improve the shearing force of the adhesive composition by interacting with the hydrophilic group (hydroxy group, etc.) of the polyvinyl alcohol-based resin contained in the adhesive composition. Moreover, the adhesiveness of an adhesive composition and a polarizer can be improved by interacting with the hydrophilic group (hydroxy group etc.) which the component which comprises the polarizer mentioned later has. As a result, the change of the stress of the adhesive composition hardly occurs, and as a result, the polarizer is hardly deformed, and polarizer cracking can be suppressed. Moreover, even if a solution component transfers inside a polarizer in a manufacturing process, since it adheres strongly with the adhesive composition which has high shear strength, a polarizer becomes hard to deform | transform, and generation | occurrence | production of an orange peel can be suppressed.

The bulk density of the fumed metal compound is preferably 0.03 to 0.10 g / cm 3, and more preferably 0.04 to 0.05 g / cm 3. When the bulk density is large, when manufacturing the polarizing plate, the fumed metal compound may be disposed in the thickness direction in the adhesive composition, so that the adhesive composition may have a constant physical strength. Thereby, the shear strength of an adhesive composition can be improved further, and generation | occurrence | production of a polarizer crack and an orange peel can be suppressed. In addition, in this specification, the bulk density shall employ | adopt the value measured by the method of the tapped bulk density.

Moreover, it is preferable that it is 100-400 m <2> / g, and, as for the specific surface area of a fumed metal compound, it is more preferable that it is 100-200 m <2> / g. When a specific surface area is large, a fumed metal compound will be in easy contact with the component which has the hydrophilic group which comprises the polyvinyl alcohol and polarizer which comprise an adhesive composition. As a result, interaction between hydrophilic groups tends to occur, and the shearing force of the adhesive composition can be improved. At this time, compared with the specific surface area of the colloidal metal compound conventionally used, since the fumed metal compound has a structure in which a metal compound having a small particle diameter is agglomerated, the specific surface area of the fumed metal compound shows a higher value. Therefore, when a fumed metal compound is used, it is easier to contact with the component which has the said hydrophilic group than when using a metal compound colloid, and an adhesive composition can have higher shear force. In addition, in this specification, a specific surface area means BET specific surface area, and shall employ | adopt the value measured by the simple BET method.

It is preferable that it is 5-50 nm, and, as for the primary particle diameter of a fumed metal compound, it is more preferable that it is 7-20 nm. If the primary particle diameter is 5 nm or more, it is preferable in that the bulk density of the fumed metal compound does not become too small. On the other hand, when the primary particle diameter is 50 nm or less, it is preferable at the point that a specific surface area does not become small too much. In addition, the said primary particle diameter shall employ | adopt the numerical value measured by a TEM (transmission electron microscope).

Content of the fumed metal compound in an adhesive composition is 20-300 mass parts with respect to 100 mass parts of said polyvinyl alcohol-type resins, Preferably it is 30-250 mass parts, More preferably, it is 30-220 mass parts. When content of the said fumed metal compound is 20 mass parts or more, it is preferable at the point that an adhesive composition has high shear force and the physical strength of an adhesive composition becomes high. On the other hand, when the content of the fumed metal compound is 300 parts by mass or less, it is preferable in that adhesiveness between the polarizer and the protective film can be sufficiently secured.

[Curing agent]

A hardening | curing agent crosslinks polyvinyl alcohol-type resin, and serves to improve a shear force.

There is no restriction | limiting in particular as a hardening | curing agent as long as it can crosslink polyvinyl alcohol-type resin, A well-known hardening | curing agent can be used. Specifically, Monoaldehydes, such as formaldehyde, acetaldehyde, a propionaldehyde, a butyl aldehyde; Dialdehydes such as glyoxal, malondialdehyde, succinic aldehyde, glutaraldehyde, maledialdehyde, and phthaldialdehyde; Metal salts of glyoxylic acid such as sodium glyoxylate and potassium glyoxylate; Alkylene diamines such as ethylenediamine, triethylenediamine and hexamethylenediamine; Tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropanetolylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis (4-phenylmethane) triiso Isocyanates such as cyanate and isophorone diisocyanate; Ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerine diglycidyl ether, glycerine triglycidyl ether, 1,6-hexanediol die Epoxy, such as glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, and diglycidylamine; Amino-formaldehyde resins such as methylolurea, methylolmelamine, alkylated methylolurea, alkylated methylolated melamine, acetoguanamine, benzoguanamine and condensate of formaldehyde; Salts of divalent metals or tetravalent metals such as sodium, potassium, magnesium, calcium, aluminum, iron, nickel, zirconium, and oxides thereof. Among these, it is preferable to use metal salts of dialdehydes or glyoxylic acid, and it is more preferable to use glyoxal or sodium glyoxylate. The said hardening | curing agent may be used independently, and may mix and use 2 or more types.

Content of the hardening | curing agent in an adhesive composition is 5-40 mass parts with respect to 100 mass parts of said polyvinyl alcohol-type resins, Preferably it is 10-35 mass parts, More preferably, it is 15-30 mass parts. When content of the said hardening | curing agent is 5 mass parts or more, it is preferable at the point by which polyvinyl al 1/2 ol is fully bridge | crosslinked and the moisture heat resistance of the polarizing plate obtained improves. On the other hand, when content of the said hardening | curing agent is 40 mass parts or less, it is preferable at the point which can fully secure the pot life (time which can apply | coat an adhesive composition in a solution state) of an adhesive composition.

[Method for producing adhesive composition for polarizing plate]

There is no restriction | limiting in particular about the manufacturing method of the adhesive composition for polarizing plates, It can manufacture by a well-known method. For example, an adhesive composition can be manufactured by mixing predetermined amount of polyvinyl alcohol-type resin and predetermined amount of hardening | curing agent in water, and adding and stirring predetermined amount of fumed metal compound in the obtained liquid mixture.

It is preferable that an adhesive composition disperse | distributes a fumed metal compound stably. In order to obtain such an adhesive composition, what is necessary is just to set pH of an adhesive composition suitably according to the fumed metal compound to be used. For example, since the silicon oxide constituting the fumed silica is neutral to weakly acidic, it is preferable to make the pH acidic. Although the well-known pH adjusters, such as hydrochloric acid and sodium hydroxide, may be used for adjustment of this pH, you may use a crosslinking agent. For example, since glyoxal has a pH of 3.3 in a 10% by mass aqueous solution, the pH of the adhesive composition can be adjusted to the acidic side by using glyoxal as the crosslinking agent. Moreover, since sodium glyoxylate has pH of 6.3 in 10 mass% aqueous solution, pH of an acidic side can be adjusted to a neutral side. According to a preferred embodiment, it is preferable to use a crosslinking agent having a pH similar to that of the metal compound constituting the fumed metal compound. Specifically, when the fumed metal compound is mainly composed of silicon oxide or aluminum oxide, it is preferable to use glyoxal as the crosslinking agent. In addition, when the fumed metal compound is mainly composed of tin oxide, it is preferable to use sodium glyoxylate.

The viscosity of the prepared adhesive composition becomes like this. Preferably it is 1-50 mPa * s, More preferably, it is 3-30 mPa * s. If the viscosity is 1 mPa · s or more, the adhesive composition is preferable in that it has a high shear force. On the other hand, when a viscosity is 50 mPa * s or less, it is preferable at the point which application becomes easy.

As needed, you may add additives, such as an adhesive, a ultraviolet absorber, antioxidant, a stabilizer, and a silane coupling agent, as needed. By adding the said additive, it can become the adhesive composition which has a desired performance.

According to another embodiment of the present invention, there is provided a piece plate comprising a polarizer and a protective film, wherein the polarizer and the protective film are bonded by the adhesive composition according to the present invention. The polarizing plate may typically have a structure in which a protective film-adhesive-polarizer-adhesive-protective film is laminated in this order. At this time, the polarizing plate may have a structure in which one protective film is omitted, that is, a protective film-adhesive-polarizer is laminated in this order.

[Polarizer]

The polarizer has a function of passing only light in a specific direction and blocking other light.

As a polarizer, if it has the said function, there will be no restriction | limiting in particular, A well-known thing can be used. Specifically, the film may be a film dyed with an iodine compound or the like and stretched in one direction. The polarizer may be further crosslinked with an additive.

As resin which can be used for a polarizer, polyvinyl alcohol-type resin can be used normally. The polyvinyl alcohol-based resin may be polyvinyl alcohol obtained by saponifying polyvinyl acetate; Polyvinyl alcohol obtained by saponifying a copolymer of polyvinyl acetate and other monomers; Modified polyvinyl alcohol and the like. The polyvinyl alcohol-based resin is the same as the polyvinyl alcohol-based resin that can be used in the polarizing plate adhesive composition described above.

The above-mentioned polyvinyl alcohol-type resin may be used independently, or may mix and use 2 or more types.

It is preferable that the polymerization degree of polyvinyl alcohol-type resin is 2000-3000. Moreover, it is preferable that the saponification degree of polyvinyl alcohol-type resin is 90-100 mol%.

The iodine compound used for the polarizer may be an iodine aqueous solution in which iodine and potassium iodide are dissolved. In addition, a dichroic dye may be used together with the iodine compound or in place of the iodine compound. As said dichroic dye, the azo dye as described in JP 2000-292780 A, JP H7-159615 A, etc. is mentioned, for example. In the present invention, the above patent is incorporated by reference.

Examples of the additive used for crosslinking the polarizer include boric acid, glyoxal, glutaraldehyde and the like. By crosslinking process, water resistance can be provided to a polarizer and color adjustment can be performed. In order to accelerate the curing, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate and the like may coexist.

A polarizer can be normally produced by immersing polyvinyl alcohol-type resin in the aqueous solution containing an iodine compound, dyeing, and then uniaxially stretching 3 to 7 times to make a polyvinyl alcohol-type film. In addition, the polyvinyl alcohol-based film may be immersed in an aqueous solution containing an iodine compound after stretching the polyvinyl alcohol resin. When performing crosslinking process with respect to the obtained polyvinyl alcohol-type film, the said polyvinyl alcohol-type film is immersed in the aqueous solution containing boric acid.

The aqueous solution containing the said iodine compound may be 0.1-1.0 mass% aqueous solution of iodine / potassium iodide. In addition, the aqueous solution containing boric acid may be a 1-10 mass% aqueous solution of boric acid.

The obtained polarizer may be washed with water further. Contamination can be removed by washing the polarizer, and staining of the polyvinyl alcohol-based film can be prevented by swelling.

[Protective film]

The protective film serves to reinforce the polarizer.

There is no restriction | limiting in particular as a protective film, A well-known thing can be used. Specific examples include cellulose resins such as cellulose diacetate, cellulose tripropionate and cellulose dipropionate; Polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; Acrylic resins such as polymethyl methacrylate; Styrene resins such as polystyrene and acrylonitrile styrene copolymer (AS resin); Polycarbonate resin; Polyolefin resins such as polyethylene, polypropylene, polyolefin having a cycloalkyl structure, polyolefin having a norbornene structure, and ethylene / propylene copolymer; Vinyl chloride resin; Amide resins such as nylon and aromatic polyamide; Imide resin; Sulfonic resin; Polyether sulfone resin; Polyether ether ketone resins; Polyphenylene sulfide resin; Vinyl alcohol-based resins; Vinylidene chloride resins; Vinyl butyral resin; Allylate series resin; Polyoxymethylene type resin; And epoxy resins. It is preferable to use cellulose resin among these, and it is more preferable to use cellulose triacetate from the point of availability or price.

The resin may be a commercially available product, and as the commercially available product, UV-50, UV-80, SH-80, TD-80U, TA-TAC, UZ-TAC (manufactured by FUJIFILM Corporation), KC series (Konica Minolta Opto) Co., Ltd.) etc. are mentioned.

The said resin may be used independently and may be used in combination of 2 or more type. Moreover, a single layer may be sufficient as the said protective film, and what laminated | stacked two or more layers may be sufficient.

[Polarizing plate production method]

The polarizing plate is not particularly limited and can be produced by a known method. For example, a polarizing plate can be manufactured by bonding a polarizer with a protective film through the solution containing an adhesive agent, and then drying. That is, the manufacturing method of a polarizing plate includes the process of apply | coating an adhesive composition, the process of sticking a polarizer and a protective film, and the process of drying.

In the process of apply | coating an adhesive composition, the method of apply | coating an adhesive composition does not have a restriction | limiting in particular, The method of dripping the adhesive composition directly, the roll coat method, the spraying method, the dipping method, etc. can be employ | adopted. In this case, an adhesive composition may be apply | coated to either a polarizer or a protective film, and may be apply | coated to both.

As a process of pasting a polarizer and a protective film, a roll laminator etc. can be used normally.

In the process of drying, drying temperature becomes like this. Preferably it is 30-100 degreeC, More preferably, it is 40-85 degreeC. Moreover, drying time becomes like this. Preferably it is 1 to 10 minutes, More preferably, it is 3 to 7 minutes. The adhesive composition apply | coated in the solution state by the drying process turns into the adhesive layer which comprises a polarizing plate by drying.

The adhesive composition containing the fumed metal compound has a higher viscosity than the adhesive composition containing the same amount of the metal compound colloid. For this reason, the adhesive composition containing a fumed metal compound can have a higher shear force in a solution state. As a result, the stress which may arise in an adhesive composition in the manufacturing process of a polarizing plate can be reduced, and a deformation | transformation of a polarizer may become difficult to occur.

It is preferable that it is 10-300 nm, and, as for the thickness of the adhesive layer of the manufactured polarizing plate, it is more preferable that it is 10-200 nm. If the thickness of the said contact bonding layer is 10 nm or more, it is preferable at the point that sufficient adhesive force is obtained. On the other hand, when the thickness of an adhesive layer is 300 nm or less, it is preferable at the point which an adhesive layer has uniform thickness. The thickness of an adhesive layer can be adjusted with the solid content concentration in the solution of an adhesive composition, and the coating device of an adhesive composition. In addition, the thickness of this contact bonding layer shall observe and measure a cross section with a scanning electron microscope (SEM).

Example

Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.

<Solid content>

The measurement of solid content of the solution in which polyvinyl alcohol-type resin is melt | dissolved was performed with the following method. About 1 g of polyvinyl alcohol-type resin solution is weighed precisely in the glass dish which weighed accurately. After drying at 105 ° C for 1 hour, the temperature is returned to room temperature (25 ° C), and the total mass of the glass plate and the remaining solids is precisely weighed. Solid content was computed by following formula 1 as X the mass of a glass dish, and the mass Z of the sum total of the glass dish and resin solution before drying as Y and the total Z of a glass dish and a residual solid content.

[Equation 1]

Example  One

&Lt; Preparation of adhesive composition >

Gocepama (registered trademark) Z Z-410 (manufactured by Nihon Kosei Chemical Co., Ltd.), an acetoacetyl-modified polyvinyl alcohol resin, was adjusted to a solid content of 2% by mass to obtain an aqueous solution. Glyoxal aqueous solution (pH 3.3) which is a hardening | curing agent adjusted to 10 mass% of active ingredients was mixed with this aqueous solution. Next, aerosol (registered trademark) Alu130 (fumed silica: specific surface area of 110 to 130 m 2 / g: volume density of about 0.04 g / cm 3: Nippon Aerosol Co., Ltd.), which is a fumed metal compound adjusted to 10% by mass of solids, was added. And dispersed using a homogenizer at room temperature (25 ° C.) to obtain an adhesive composition solution. The obtained adhesive composition solution was 30 mass parts and 15 mass parts of fumed metal compounds with respect to 100 mass parts of polyvinyl alcohol-type resins.

Example  2

The adhesive composition solution was prepared by the method similar to Example 1 except having changed the addition amount of a hardening | curing agent and a fumed metal compound. The obtained adhesive composition solution was 80 mass parts and 20 mass parts of fumed metal compounds with respect to 100 mass parts of polyvinyl alcohol-type resins.

Example  3

The adhesive composition solution was prepared by the method similar to Example 1 except having changed the addition amount of a hardening | curing agent and a fumed metal compound. The obtained adhesive composition solution was 150 mass parts and 20 mass parts of fumed metal compounds with respect to 100 mass parts of polyvinyl alcohol-type resins.

Example  4

The adhesive composition solution was prepared by the method similar to Example 1 except having changed the addition amount of a hardening | curing agent and a fumed metal compound. The obtained adhesive composition solution was 220 mass parts and 30 mass parts of fumed metal compounds with respect to 100 mass parts of polyvinyl alcohol-type resins.

Example  5

Aerosil (registered trademark) MOX170 (silicon oxide / aluminum oxide mixed fumed metal compound in which the amount of the curing agent was changed and the fumed metal compound was adjusted to 10% by mass of solids: surface area 140 to 200 m 2 / g: bulk density about 0.05 g / cm <3>: The adhesive composition solution was prepared by the method similar to Example 1 except having changed into the Nippon Aerosol Co., Ltd. product. The obtained adhesive composition solution was 50 mass parts and 20 mass parts of fumed metal compounds with respect to 100 mass parts of polyvinyl alcohol-type resins.

Example  6

The adhesive composition solution was prepared by the method similar to Example 5 except having changed the addition amount of the mixed fumed metal compound. The obtained adhesive composition solution was 100 mass parts of fumed metal compounds and 20 mass parts of hardening | curing agents with respect to 100 mass parts of polyvinyl alcohol-type resins.

Comparative example  One

The adhesive composition was prepared by the method similar to Example 1 except having changed the addition amount of the hardening | curing agent and not adding a fumed metal compound. The obtained adhesive composition solution was 10 mass parts with respect to 100 mass parts of polyvinyl alcohol-type resins.

Comparative example  2

The adhesive composition solution was prepared by the method similar to Example 1 except having changed the addition amount of a hardening | curing agent and a fumed metal compound. The obtained adhesive composition solution was 15 mass parts and 10 mass parts of fumed metal compounds with respect to 100 mass parts of polyvinyl alcohol-type resins.

Comparative example  3

The adhesive composition solution was prepared by the method similar to Example 1 except having changed the addition amount of a hardening | curing agent and a fumed metal compound. The obtained adhesive composition solution was 320 mass parts and 40 mass parts of fumed metal compounds with respect to 100 mass parts of polyvinyl alcohol-type resins.

Comparative example  4

The adhesive composition was prepared by the method similar to Example 1 except having changed the addition amount of the hardening | curing agent and not adding a fumed metal compound. The obtained adhesive composition solution was 40 mass parts with respect to 100 mass parts of polyvinyl alcohol-type resins.

Comparative example  5

Except for changing the addition amount of the curing agent and changing the fumed metal compound to 10% by mass of solids and changing to aluminum solution 1-10A (aluminum oxide colloid: manufactured by Kawaken Fine Chemical Co., Ltd.) which is a colloidal metal compound. , An adhesive composition solution was prepared in the same manner as in Example 1. The obtained adhesive composition solution was 80 mass parts and 20 mass parts of metal compound colloids with respect to 100 mass parts of polyvinyl alcohol-type resins.

The compounding ratio (active ingredient ratio) of the material of the adhesive composition solution prepared in Examples 1-6 and Comparative Examples 1-5 is shown in Table 1 below.

&Lt; Production of polarizing plate &

The polarizer was created by the following method. That is, polyvinyl alcohol (average degree of polymerization 2400, saponification degree 99.9%, thickness 75 µm) is swelled by immersion in hot water at 28 ° C for 90 seconds, and then swelled at a concentration of 0.6% by mass of iodine / potassium iodide (mass ratio 2/3). It was immersed in the aqueous solution of and extended by 2.1 times, and the polyvinyl alcohol film dyed with iodine was obtained. Thereafter, the polyvinyl alcohol film was stretched in the boric acid ester aqueous solution so that the draw ratio in total was 60 times. After washing with water, the mixture was dried at 45 ° C. for 3 minutes to prepare a polarizer.

As a protective film, the triacetyl cellulose (TAC) film (thickness 80 micrometers) was used.

Manufacturing example  One

As shown in Fig. 1, a polarizer (thickness: 80 µm) prepared between TAC and two films is sandwiched between the polarizing plates, and a suitable amount of the adhesive composition solution obtained in Example 1 is dropped on both surfaces of the polarizer with a dropper, followed by a roll press. It bonded together and obtained the polarizing plate before drying. In addition, the arrow of FIG. 1 shows the moving direction of a polarizer, an adhesive composition, and a TAC film. The obtained polarizing plate before drying was dried for 5 minutes at 70 degreeC, and the polarizing plate which has a structure which TAC film-adhesive layer-polarizer-adhesive layer-TAC film laminated in this order was produced.

Manufacturing example  2 ~ 11

The polarizing plate was manufactured by the method similar to the manufacture example 1 using the adhesive agent prepared in Examples 2-6 and Comparative Examples 1-5.

<Evaluation of Polarizer>

The produced polarizing plate was evaluated by observation of an orange peel, a thermal shock test, an optical characteristic measurement, a cutting test, a forced peeling test, and a moisture-resistant heat test.

(Observation of the orange peel)

The external appearance of the polarizing plates manufactured in Production Examples 1 to 11 was visually observed, and the presence or absence of orange peel was observed.

When the orange peel was remarkably visible, it was judged that the appearance was poor, and when the orange peel was hardly visible, the appearance was judged to be good.

(Thermal shock test)

The polarizing plates produced in Production Examples 1 to 11 were cut to 5 cm x 5 cm with a Thomson blade, and were used as test pieces. Subsequently, as shown in Fig. 2 (a), the test piece was bonded to a SUS plate polished with a water-resistant abrasive (# 280) using a temporary adhesive Aaron Alpha (registered trademark) for general use (manufactured by Toagosei Co., Ltd.), Aged 24 hours at room temperature (25 ℃). The thermal shock test was done about the aged test piece. In addition, a thermal shock test repeats 30 cycles to stand at 85 degreeC for 1 hour and -40 degreeC for 1 hour.

After giving a thermal shock, as shown in FIG.2 (b), it observed whether a polarizer crack exists from the edge part of a polarizing plate in the extending direction of a polarizer, and when the polarizer crack was observed, the length of the crack was measured. When two or more cracks are observed, it shall evaluate using the average value. If the length of a crack is less than 0.5 mm from an edge part, it can be judged that polarizer crack by a thermal shock can be prevented.

<Optical characteristics>

About the polarizing plates manufactured in Production Examples 1-11, the transmittance | permeability and haze were measured using the haze meter (Haze Meter NDH500W: Nippon Denshoku Kogyo Co., Ltd. product).

It is judged that it is suitable for actual use as a polarizing plate as it is 43% or more about transmittance | permeability and 0.5% or less about haze.

<Test of Foundation>

The polarizing plates manufactured in Production Examples 1 to 11 were cut to 5 cm x 5 cm with a Thompson blade, and the peeling state of the edge part at the time of cutting was observed visually.

It was judged that there was no peeling if the length of peeling was less than 0.5 mm from the edge part, and it was judged that there was peeling if it was 0.5 mm or more.

Forced Peel Test

As shown in FIG. 3, the sheath (half cut) was put into the TAC film of one surface of the polarizing plates manufactured in Production Examples 1-11 with a knife. Next, it deform | transformed until the bending of a polarizing plate generate | occur | produced so that a half cut part might become a convex side. Then, the state of peeling of the TAC film of the location where a bending generate | occur | produced was observed visually.

When no peeling was observed, it was judged that there was no peeling, and when peeling was observed, it was judged that there was peeling.

&Lt; Heat and humidity test &

The polarizing plates manufactured in Production Examples 1-11 were cut out to 5 cm x 5 cm with the Thompson blade, and it was set as the test piece. This test piece was stored for 3 hours in the atmosphere of 60 degreeC and 99% RH, and the shrinkage width of the polarizer after that was measured.

It was judged that there was no problem if the shrinkage width was less than 0.5 mm, and there was a problem if the shrinkage width was 0.5 mm or more.

The obtained evaluation results are shown in Table 2 below.

As can be clearly seen from Table 2, orange peel was hardly observed in the polarizing plates produced using the adhesive compositions of Examples 1 to 6, and the appearance was good. On the other hand, orange peel was remarkably observed in the polarizing plate (production example 11) manufactured using the conventional adhesive composition (production example 5) containing the metal compound colloid like what is used by patent document 1.

In addition, the polarizing plates (Manufacture Examples 1-6) manufactured using the adhesive composition of Examples 1-6 were able to suppress a polarizer crack and were few even if a polarizer crack generate | occur | produced. This polarizer crack suppression effect is compared with the polarizing plates (Manufacture Examples 7 and 10) manufactured using the adhesive composition which consists only of polyvinyl alcohol-type resin and a hardening | curing agent, and the conventional adhesive composition (Manufacture Example 5) containing a metal compound colloid. It can be said that it has high polarizer crack suppression effect.

In contrast to the polarizing plates (Manufacture Examples 1 to 4) prepared using the adhesive compositions of Examples 1 to 4 and the polarizing plates (Manufacture Examples 8 and 9) prepared using the adhesive compositions prepared in Comparative Examples 2 and 3, When a large amount of the fumed metal compound is contained in the adhesive composition, generation of orange peel of the polarizing plate can be suppressed, but the results of the cutting test, the forced peel test, and the heat resistance test show that the adhesiveness is not sufficient. On the other hand, when there were too few fumed metal compounds in an adhesive composition, although adhesiveness was enough, generation | occurrence | production of orange peel could not fully be suppressed.

Claims (9)

100 parts by mass of a polyvinyl alcohol-based resin;
20 to 300 parts by mass of the fumed metal compound; And
Adhesive composition for polarizing plates containing 5-40 mass parts of hardening | curing agents.
The polarizing plate adhesive composition of claim 1, wherein the bulk density of the fumed metal compound is 0.03 to 0.10 g / cm 3.
The polarizing plate adhesive composition of claim 1, wherein a specific surface area of the fumed metal compound is 100 to 400 m 2 / g.
The metal compound of claim 1, wherein the metal compound included in the fumed metal compound is silicon oxide (SiO 2), aluminum oxide (Al 2 O 3), titanium oxide (TiO 2), tin oxide (SnO 2), zinc oxide (ZnO 2), or zirconium oxide (ZrO 2). And at least one of cerium oxide (CeO 2).
The polarizing plate adhesive composition of claim 1, wherein the fumed metal compound has at least one hydrophilic group.
The polarizing plate adhesive composition of claim 1, wherein the primary particle diameter of the fumed metal compound is 5 to 50 nm.
The method of claim 1, wherein the curing agent is monoaldehyde; Dialdehydes; Metal salts of glyoxylic acid; Alkylene diamines; Isocyanates; Epoxy; Amino-formaldehyde resins; And salts of divalent metals or tetravalent metals and oxides thereof.
The polarizing plate adhesive composition of claim 1, wherein the polarizing plate adhesive composition has a viscosity of 1 to 50 mPa · s.
The polarizing plate containing a polarizer and a protective film, Comprising: The said polarizer and the said protective film are adhere | attached by the adhesive composition for polarizing plates in any one of Claims 1-8.

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